Definition 2.7 [1]} If we mutate an \(n\times n\)  exchange matrix \(B = (b_{ij})\)  at \(k\)  we obtain \(B^{\prime } = (b^{\prime }_{ij})\)  defined here.
\(b^{\prime }_{ij} = {\left\lbrace \begin{array}{ll}-b_{ij} & \text{if }i = k\text{ or }j = k\\b_{ij} + b_{ik}|b_{kj}| & \text{if }b_{ik}b_{kj} > 0\\b_{ij} & \text{in all other cases}\end{array}\right.}\)

